1. Field of the Invention
This invention relates in general to industrial heat treating furnaces and in particular to a system for transporting a large work load into and out of a heat treating furnace.
2. Description of the Related Art
The load capacity of industrial heat treating furnaces has increased substantially over the last several years. The increase in the size of the work load that can be handled in a single furnace presents practical problems in loading and unloading the work load to be heat treated. For example, the use of fork lifts and other types of lift devices has proved inadequate for heavy, elongated work loads. The clearances inside the known vacuum heat treating furnaces are so close that damage to the heating elements, the work load supports, or other protruding components often results. Moreover, the stanchions that support the work load inside the furnace must be designed to resist transverse (bending) forces during horizontal translation of the work load inside the furnace.
One proposed solution to the problem of handling such large work loads is described in U.S. Pat. No. 6,936,792. That patent describes a load transfer cart which forms a part of the vacuum furnace itself. However, the apparatus described in that patent has inherent disadvantages. For example, the bottom heating elements of the heat treating furnace are integrated with the load transfer cart and thus, must be connected and disconnected with each load transfer. Also, the bottom section of the hot zone enclosure must be integrated with the transfer cart which adds to the complexity of the design. Further, the wheel bearings used on the transfer cart must be resistant to the high temperatures inside the heat treating furnace because the entire cart, including the wheels and bearings, remains inside the furnace during a heat treating cycle.
In view of the problems described above, it would be desirable to have a solution to the shortcomings of the known techniques and equipment for loading and unloading large, a heavy work load in a heat treating furnace.